Two hours before dawn, and the valley's blast-furnace heat was already intensifying. Four men padded along a dirt road. A half-mile away, flatbed trucks made their way along Highway 83, a narrow strip of asphalt near the U.S.–Mexico border, angling north and west from the Gulf Coast.

The men raised their binoculars briefly to watch a satellite move across the horizon. "You think they threw us a red herring?" The men had been told they could see a common poorwill here, but after a few minutes of searching, Michael Manson was beginning to wonder. The tip had come from a competitor. "No," he said, answering his own question. "They wouldn't do that."

Not even to gain an edge in what has become the Ironman of birding marathons: the Great Texas Birding Classic.

Each spring along the state's 500-mile Gulf Coast, from Brownsville to the Louisiana border, teams of three to five birders battle for five straight days—sleeping optional—to see who can bag the most bird species. At stake are bragging rights and $50,000, which will be spent on habitat conservation. By the time the dust finally settles over sanctuaries up and down the coast, sponsorship money will have been distributed to projects ranging from the acquisition of bottomland hardwood forest to the restoration of tallgrass prairie.

"From a conservation standpoint, you couldn't ask for a better event,"says Jesse Grantham, Audubon's director of bird conservation for Texas and a participant in a one-day variation on the main event. "The Classic has a product at the end other than just a long list of birds. You come back with something accomplished."

From a birding perspective, you couldn't ask for a better venue. More than 75 percent of all bird species occurring in the continental United States have been reported in Texas—about 600 in all. These include migrants from Mexico and Central and South America as well as vagrant species that wander over the border.

The experience is addictive. Manson, a biology professor at Texas A&M, was competing for his fourth straight year, as was A&M bioacoustics specialist Scott Brandes. Their team, the Zeiss Guys (sponsored by the binoculars maker), also fielded two newcomers: A&M graduate students Damion Marx and Karl Kosciuch.

Right now all four were frustrated. The poorwill was nowhere to be seen, and other competitors were arriving, along with the sun. A dusty Ford Explorer driven by Nicholas Block, 21-year-old captain of the Classic's youngest team, the Third-Basic WildBirders, and a onetime student at Rice University in Houston, pulled up.

"So, where'd you end up yesterday?" Block asked Manson. Silence.

"What, do you think I'll steal your birds?"

"Yeah," said Manson, only half-joking. The Zeiss Guys moved down the road. Roosters began to crow around nearby homes. Manson pursed his lips just so and let out a soft exhalation. The response: a gentle, onomatopoeic whistle. "That's it," Manson said. "Let's go!"

Day 2: Zapata Brief pit stop for the Zeiss team. A sun-beaten digital thermometer above a bank reads 115 degrees. Milk shakes are critical fuel for competition. Dairy Queens up and down the Great Texas Coastal Birding Trail, which the Classic traces, benefit from the thirst-driven participants. This year 236 people from California to Rhode Island, and from seasoned adults to "roughwings" (aged 8 to 13), competed in either the full five-day tournament or single-day contests. Since the event attracts a growing number of nature tourists to the birding trail, communities en route that have preserved habitat for good birding are able to cash in.

"Many of these communities are rural," points out Shelly Scroggs, who coordinates the Classic for Texas Parks & Wildlife. "And birders travel during the nontypical travel season. By putting prize money back into the trail, we're hopefully creating new sites and new opportunities for communities along the coast to feed their economies year-round."

The Classic is said to be the "biggest, longest, and wildest" birdwatching tournament in the United States—and this year it became even more fanatic. Contestants used to bird for three 24-hour days in different coastal regions, spaced out by two days of nonbirding rest. But since most teams spent that downtime scouting, the staff changed the Classic to an official free-for-all. Now teams can bird anywhere in Texas's 41 coastal counties, for the duration of the event.

Which means that for most teams, moments of avian pandemonium—seven or eight species in a few minutes—are punctuated by intervals of driving, driving, and more driving. The Classic is not so much about science as sport, and one that ratchets up the profile of birding from a leisurely pastime to a pursuit a little nearer the Cannonball Run. A British tourist marveled at the Zeiss team during a roadside chat. "You're not birdwatching," he said. "You're bird racing!"

Before Zapata's scorching heat drove them indoors, the Zeiss Guys ranged across a small park near the Rio Grande's Falcon Dam, searching for a black-tailed gnatcatcher. The local rare-bird alert had reported several nesting there.

The group quickly saw a Couch's kingbird and a Bullock's oriole, and got a good telescope view of a crested caracara—fairly spectacular, with a hawk's silhouette mated to a vulturelike, carrion-tearing beak—soaring above the dam, which divides the Rio Grande into lazy wetlands on one side and a vast reservoir on the other. But the gnatcatcher, a bird the team would be unlikely to see anywhere else, remained elusive. "The toughest thing is to decide how much effort to expend on one species," said Manson.

The group headed toward the El Rio RV park, a trailer camp that bills itself as a birder's paradise. Another team rumbled by, throwing up a cloud of dust. The Zeiss squad scanned the chaparral. Something fluttered from the brush—a fist-size bird, mostly gray, with a black tail and the matching spring-plumage cap—and Kosciuch shouted, "Gnatcatcher! Gnatcatcher!"

"Play of the day," screamed Marx. High fives all around.

Day 3: Port Aransas Nick Block and the WildBirders were considering a gamble.

To win a birding race, you need more than speed. You need to scout, learning where the local birds are, and to network, gathering intelligence about conditions along the coast. You need to bird with people who work well together. And you need to plan your route carefully.

Or, just maybe, you need to risk it all.

The year before, Block had been on the winning team with another young birder, 22-year-old Cameron Cox. The two had planned to join forces again, but Cox moved, and when Block couldn't find him, he was forced to form a new squad. (Cox later resurfaced on another team, Birds Galore!) Block's first enlistee was a 19-year-old freshman at the University of Texas, Graham Gips. He had competed in birding events before (that was good). His dad was willing to lend his Ford Explorer (that was better).

Until a week before the event, neither 17-year-old Christian Nunes, a high school student from Rhode Island, nor 19-year-old Matt Hafner, a University of Maryland student, had met Block in person or, for that matter, even been to Texas. They had grown acquainted through the online Teen BirdChat listserv. Block had chosen the pair for his team carefully. He was certain they brought skills he and Gips lacked; many of the migrant birds that touched the Texas coast were native to Nunes's and Hafner's home areas.

The team's primary strategy was to use its youth to the fullest advantage. No WildBirder ever slept more than four to five hours straight during the entire event; only two nights were spent in motels. When Gips returned his father's Ford, it had nearly 3,300 new miles on it. The WildBirders put their driving time to good use, scouting dozens of nesting species and then using the nights to spot them. That left the daytime open for a bet-the-house tactic.

The WildBirders debated their day-three plans right up until the final moments. The Classic has always allowed competitors to extend their hunt into the Gulf of Mexico, but no team had ever actually tried it. It was too risky; it could cost nearly an entire day. Block estimated that a water trip could net up to four extra birds—or it could yield nothing. The WildBirders decided that if they did well the first two days and could find a boat in Port Aransas that would return to land by 4:00 p.m.—giving them a good part of the evening to keep birding—they might hazard it.

At 7:00 that morning, the teammates joined 20 other passengers, all fishermen, and steamed out into the Gulf. The adventure hadn't gone off in total secrecy, however. They had been spotted on the dock, and by afternoon the news was out. The consensus was that Block's team had made a mistake. "To me,"Brandes recalls, "they'd seriously compromised their chances. I didn't see how a trip like that could be productive."

When the WildBirders returned at 3:30 that afternoon, they didn't say a word.

Day 4: High Island Bird Sanctuary The contest's only all-woman squad—sisters Cecilia Riley, executive director of the Gulf Coast Bird Observatory, and Joan Holt, a marine biologist at the University of Texas, and their friend Jane Kittleman, a retiree from the town of McAllen—had competed in every Birding Classic since the inaugural event in 1997. Their best finish, third place, had come in 2001, and they had entered this year as Team Realtree Roadrunners. Realtree, a maker of camouflage clothing, had also attired them, making them extraordinarily easy to pick out, even in the sanctuary crowds.

The three women maneuvered past the amphitheater bleachers surrounding Purkey's Pond (rest rooms and souvenirs to the right; yellow warblers and rose-breasted grosbeaks straight ahead) to a jasmine-scented area that's known as the Cathedral. Here, among the branches of a willow tree, they identified a Tennessee warbler by the preponderance of green on its back. This migrant, which had eluded the team earlier, was a good catch.

Moving on to High Island's largest open area, the Smith Oaks Bird Sanctuary, they joined a steady stream of visitors making their way down a dirt trail. Just around the bend, they found thousands of herons, cormorants, egrets, and roseate spoonbills covering a tiny island at the center of a pond, obscuring trees, water, even sky. The island seemed almost like one undulating bird, or a spattered paint spill, as the deep blacks and whites of the herons and egrets merged with the luscious pinks of the spoonbills. The rookery was humming; the combined calls of thousands of birds seemed to blend into a nearly seamless mega-sound, harmonic and dissonant at once, broken only by a stray coo or squawk from a hungry hatchling.

The assembled birders—dozens of them—were stunned, awestruck. For every adult bird, there seemed to be a half-dozen offspring, bobbing in and out of nests. For a moment, the contest was forgotten. Then a voice bellowed: "Hey! There's an anhinga over there!"

All day Riley, Holt, and Kittleman had been smarting over an earlier missed opportunity to bag this gawky marsh bird. Now they clattered across the boardwalk and spotted it just above glassy Smith Pond; the three-foot anhinga, with its long, snakelike neck, hung for a moment, then alit on a stump, assuming its classic hood-ornament posture, wings spread for drying.

In the past it had taken about 300 birds to win the Classic. And although it didn't look like either the Zeiss Guys or Team Realtree would approach that number, it didn't seem to matter. Not at that moment anyway. Each new bird was a tiny victory.

Day 5: Port Arthur "Seriously? Counting birds?" The leather-jacketed biker raised one eyebrow. The red bandanna tied around his forehead lifted slightly. In the lobby, a few feet away, Texas wildlife officials were setting up the judge's station for the Classic, which would end at noon, just a few hours away. "Counting birds?" the biker repeated. "You mean, like vultures and shit?"

The teams had begun the event's final day up north, mostly mopping up, staying near enough to Port Arthur to turn in their lists on time but trying to fill in the blanks on individual counts. The Zeiss team began the day inland, at a forested state park, where they had camped the night before. Team members had slept badly. And now their attempt to spot a Carolina chickadee was being thwarted by the nonbirders in a nearby campsite. It wasn't just the classic rock blaring from a portable radio. It was a highly misplaced sense of tidiness: The "outdoorsmen" were sweeping away the detritus at the campsite with a gas-powered leaf blower. "Our victory," Manson observed in a dry monotone, "is not yet secure."

Besides, perhaps, whether vultures are countable (two species are), the question most folks pose about competitive birding concerns honesty. What makes the teams tell the truth? The event's foundation is a more than 370-species official checklist. The birds on it are species that participants are likely to see (although nobody spots them all). The trickier birds also occupy a secondary list of more than 120 so-called Texas Review Species. When teams claim to have seen one of these birds, they're required to submit a report form for rare species. Birds not on either list require additional documentation, usually photographs. Judges can reject a sighting if they don't find the team's evidence convincing.

Other key regulations: Sound identification is acceptable, but attracting birds with audiotaped birdcalls is not. Every team member must see 95 percent of its listed birds (the remainder can be sighted by as few as two spotters). Team members must stay within shouting distance of one another at all times. Cell phones aren't allowed. Sick birds count; dead ones don't.

The teams straggled in. Team Realtree reported 284 species, but Riley was still frustrated over the team's failure to see a white-tailed kite. "Six hundred miles of coast," she said, "and still none!" At about 11:00 Brandes appeared with the Zeiss list. He looked spent. "It was fun,"he groaned. The count: 264.

Nick Block and the WildBirders arrived at 11:54. By this time, their pelagic gamble was common knowledge; whether or not it had paid off was still unclear. Chief judge Cliff Shackelford, nongame ornithologist for Texas Parks & Wildlife in Austin, doubted the voyage would make a difference. "The margin of victory is never neck and neck," he said. "It's usually at least five to seven birds."

Except for this year.

The team Block had been most worried about was sponsored by Swarovski. Its members were experienced, older, and had the fatigue-cutting benefit of a noncompeting driver. Team Swarovski's final tally—300—was good enough to win in many other years. With the five-day format, however, it was worth just a tie for fifth place. The fourth- and third-place squads saw 301 and 308 species, respectively. The two top places were taken by the two youngest teams. Cox and Block, who had planned to compete together, who had been separated by circumstance, both scouted extensively. Both slept little.

But only one team spent eight hours at sea. During the first hour of the voyage, Block and his teammates saw a sooty tern—a bird that doesn't even make the Review Species list. An hour later, as the fishermen were casting for snapper, a flock of gulls swarmed the boat. A pomarine jaeger—with its four-foot wingspan and jet-black head and back—swooped in. It's on the event's master checklist, but no other team reported one. Despite the promising start, for the next five hours the WildBirders saw nothing. They returned to Port Aransas with just two new birds.

Still, taking the ocean trip was only half of their hoped-for winning strategy. Opting for the voyage meant skipping the legendary birding spot of South Padre Island—it was simply too far away from the port. Fine, Block thought. Instead, he spent weeks scouting a spot nearer to the boat dock. None of the teammates would tell exactly where they went, or what or how many birds they saw. Only the final tally would reveal if the move has pushed them into the lead.

The competitors went to bed. The judges counted. At an awards brunch the next morning, the winners were announced. The five-day event had been decided by just four birds. Cox's squad, Birds Galore!, saw 321.

Block's squad saw 325.

The WildBirders were ecstatic. And all of the teams gathered at the brunch (only Manson, utterly exhausted and collapsed in his hotel room, was missing) were surprised and slightly tickled to see the two youngest teams, as Brandes put it, "kick so much ass."

The WildBirders' $20,000 first prize was awarded to the Packery Channel Sanctuary Acquisition Project (as was the $3,000 prize Jesse Grantham's team won in the single-day Central Coast competition). The Packery Channel project has received prize money from the Classic for three years running and uses it to purchase undeveloped housing lots on North Padre Island, preserving them as valuable habitat for migratory songbirds.

"As a bird flies across the gulf, this island is the first piece of land it comes to," says Leah Pummill, president of the Audubon Outdoor Club of Corpus Christi, which sponsors the project. "These lots have the only grasslands left on the island that are not surrounded by an abundance of houses, and the last standing group of scrub oaks for the next 113 miles."

The prize money could not have come at a better time. A plan has been approved to cut a channel through the island chain, providing boaters with quick access to the gulf; the lots will soon become attractive habitat for hotels, too. "We're trying to purchase ahead of the curve," Pummill said. "We're keeping our fingers crossed that we beat the bulldozers." Saving habitat, all along the trail, is the region's real contest. And if a little bird racing (and not a lot of sleep) can make a difference in those efforts, that will be the biggest victory of them all.